Headlamp lens



R. N. FALGE HEADLAMP LENS June 7, 1932.

Filed Dec. 2, 1929 Zlwuentoz lobar? 72 549a Fatented June 7, 1932 UNITED STATES PATENT OFFICE ROBERT N. FALGE, OF DETROIT, MICHIGAN, ASSIGNOR TO GENERAL MOTORS RESEARCH CORPORATION, 015' DETROIT, MICHIGAN, A CORPORATION OF DELAWARE HEADLAMIP LENS Application filed December 2, 1929. Serial No. 411,089.

This invention relates to an improved lens for automobile headlights which is so formed as to improve the light distribution of, and

require less hand work in production than is 5 required by present somewhat similar lenses. It has become quite common practice to provide vertically positioned convex flutes on either the inner or outer surface of the lens.

for the purpose of spreading the light rays 10 laterally to illuminate the sides of the road 15 One form of such known lenses provides vertical flutes on the inner surface, portions of which at the top and bottom zones are of greater depth than those portions in the intermediate central zones. In forming a lens 20 mold for a lens of this form it has been customary to employ three arbors on each of which a gang of milling cutters are assembled of proper dimensions to cut the size and number of flutes desired. The first operation is to take the arbor which cuts the shallow flutes in the central zone and run it completely across the face of the mold, and then run the other two arbors in the desired distance from the top and bottom toward the center to cut the deeper flutes in the top and bottom zones. This leaves substantially rounded end sections where the latter arbors are lifted and these sections have heretofore been taken off by hand so that there results a single transition line between respective zones.

My invention consists. with reference particularly to this type of lens, in improving the light distribution and eliminating a large amount of the hand work required in production thereof, by leaving certain of said end sections in their rounded form, and in the preferred embodiment, modifying the round ed form of certain of said end sections.

By providing rounded ends at the junction of the top and bottom zonesand the central zone, there are produced upper and lower transition zones in the lens, the effect of which is to tilt the rays passing through such transition zones and spread the rays laterally. The rays passing through the lower transltion zone are tilted downwardly and spread laterally which is desirable for illuminating the foreground. The rays passlng through the upper transition zones are tilted upwardlv and spread laterally. This latter effect is desirable from the standpoint of adding to the illumination of signs and other objects above the right side of the road but is undesirable in directing rays upwardly to the left because of resulting glare to approaching drivers. This objectionable feature has been corrected according to the preferred embodiment of my invention, as will be disclosed hereafter.

In the upper transition zones the upwardly deflected rays which are directed to the right of the car axis come from the left half of the rounded flute ends, whereas the upwardly deflected rays which are directed to the left of the car axis come from the right half of the rounded flute ends. The left half of the rounded flute ends in the upper transition zone I prefer to leave in such rounded and converging form whereby the rays passing therethrough will illuminate the right side of the road at considerable height. The right half of the rounded flute ends I finish up in the manner heretofore employed with respect to the whole end portion whereby this half presents a single transition line and rays pass ing through this half end portion will be directed laterally to the left without upward deflection such as would cause. glare to approaching drivers. The method of finishing the mold to form the upper flute ends of this character would consist in first forming the ends rounded according to the cutter-shape on removal thereof, as set forth heretofore, and then finishing up the one half of each rounded end by working out a hollow therein by hand, which would be substantially quarter round in cross section terminating in an abrupt fiat shoulder.

Throughout the preceding description I have employed the term flute with respect to both the lens and mold. It will be understood that the flutes in the mold would be preferably concave so as to produce convex flutes on the lens, as is shown in .the accompanying drawing, in which:

Fig. 1 is a rear face view of an improved typve' of lens.

g. 2 is an enlarged perspective of a portion of the lens face includlng a portion of one of the transition zones.

Figs. 3 and Aareviews corresponding to Figs. 1 and 2 of the preferred embodiment of my invention. p

Fig. 5 is an enlarged cross section taken on line 5-5 of Fig. 4.

Referring first to'Figs. 1 and 2, the lens 1' byrays passing therethrough are directed laterally to the left but not upwardly. The right halves of the ends so formed present a single transition line, whereas the left halves present a transition zone of vertical extent equal to the length of the converging portions, noting that'the lower extent of such transition zone and the single transition lines constitute together a straight horizontal line at the extreme ends of the flutes, or the enlarged portions thereof. Such a lens may be produced by a mold finished as has heretofore een disclosed.

is provided with a central vertically fluted In this preferred embodiment when considsection 2, top vertically fluted sections 3 and 4 and a bottom verticall fluted section 5, which sections are prefera ly of substantially the extent indicated. The portions of the flutes or the flutes in the top and bottom sections are of greater depth than those in the central section as may be seen from Fig. 2. The upper and lower transition zones between sections, of the vertical extent indicated at A and B, respectively, consist of the rounded converging ends 6 and 6' of the larger flutes or flute portions of the general shape shown in Fig. 2, the rounded ends of the top zone being directed downwardly and those of the bottom zone directed upwardly. The eflect of the transition zones so formed is to direct rays passing through the upper transition zone upwardly and laterally, and rays passing through the lower transition zone downwardly and laterally. This form, though advantageous in that it minimizes the hand work on the mold by which it is produced, is objectionable in light distribution, as has been heretofore set forth, in that the right halves of the rounded ends in the upper transition zones direct rays upwardly to the left such as would cause glare to approaching drivers.

To overcome this objection, I have designed the lens shown in Figs. 3, 4 and 5 which illustrate the preferred embodiment of my invention. In such figures, all elements are similar to those of Figs. 1 and 2 and are so designated, except for the form of the flute ends in the upper transition zones. The left half 7 of the end of each of the top flutes or enlarged portion thereof in the upper zones assumes the same rounded converging form as that previously described whereby the rays passing therethrough are directedupwardly and laterally to the right. The right half 8 thereof is formed by continuing the same so that its cross section at any point issimilar to that of half of the main portion of the flute as shown clearly in Fig. 5, which cross section extends to a point in line with the extreme end of the rounded converging left half where it terminates in a horizontal shoulder. In other words, the right half is continued in half fluted form to a single transition line, Whereered with those features common to the first described form, I have provided the lens with vertical flutes or enlarged portions of vertical flutes, terminating in horizontal planes above and below the center of the lens, with the end portions above the centerformed to direct rays passing therethrough upwardly in the-scope of the invention which consists basically in forming vertical flute end portions so as to direct rays passing therethrough in various directions as particularly set forth hereabove. Such structure may obviously be employed without other forms of vertical flutes such as the shallower flutes disclosed herein, and may 'be combined with any 1-;

other arrangement of lensv surface treatment such as the provision of horizontal flutes or prisms'or other forms of vertical flutes, as may be desired.

claim: 3

1. A lens provided with vertical flutes which extend from the top of the lens to above the center thereof, one half of the end portion of each flute converging in rounded form with respect to the face of the lens and with respect to the other half which is extended to the end of the first half without converging, whereby rays passing through said end portion will be directed upwardly and laterally to one side by said converging half, and laterally to the other side by said extended half.

2. A lens provided on its rear face with vertical flutes, certain of-said flutes extending upwardly from the bottom of the lens and terminating in upwardly directed converging rounded end portions below the center of the lens face whereby to direct rays passing through said end portions downwardly andlaterally to both sides, and certain of said flutes extending downwardly from the top of the lens and terminating in end portions above the center of the lens face, the left half of the end portion of each of said latter flutes being directed downwardly in converging rounded form whereby to direct rays passing therethrou h upwardly and laterally to the right si e, and the right half bein extended to the end of the left half in hal fluted form whereby to direct rays passing therethrough laterally to the left with no elevation.

3. A lens provided with a symmetricall convex flute merging at one end portion wit the face of the lens, wherein one half of said flute end portion terminates in a half flute cross section, and the other half of said flute end portion converges in rounded form from a plane spaced from the end of the first half to a point joining therewith at the inner bottom corner of the half flute cross section.

4. A lens provided with vertical flutes wherein the endportion of each flute is unsymmetrically formed, one half of the surface thereof constituting substantially a segment of a cylinder and the other half constituting substantially a segment of a cone.

5. A lens provided with vertical flutes extending downwardly from the top of the lens and terminating in end portions above the center of the lens face, the left half of the end portion of each of said flutes being directed downwardly in converging rounded form whereby to direct rays passing therethrough upwardly and laterally to the right, and the right half of 'the end portion of each of said flutes being extended to the end of the left half in half fluted form whereby to direct rays passing therethrough laterally to the left with no elevation.

6. A lens provided with a vertical convex flute having one half of a portion thereof converging downwardly in rounded form whereby to direct rays passing therethrough upwardly and laterally to one 'side and the other half of said portion of half flute form whereby to direct rays passing therethrough laterally to the opposite side with no eleva- In testimony whereof I aflix my signature.

ROBERT N. FALGE. 

